Backend refactor leaves example config broken

[duck-rh]

Quack,

Changes in 815d8c3 also change how the schedule config is organized but do not update config/default.yaml. The program also do not complain with old keys lying around and honestly the trace is not very easy to understand until you read the code.

I used the latest docker image and should probably have stayed with a tag but it's one year old already.

For the record I was trying to use the JSON backend, commented pentabarfDefinition and got this:

matrix-confbot[172056]: /app/lib/backends/penta/db/PentaDb.js:25
matrix-confbot[190167]: const PEOPLE_SELECT = "SELECT event_id::text, person_id::text, event_role::text, name::text, email::text, matrix_id::text, conference_room::text, remark::text FROM " + ((_a = config_1.default.conference.schedule.database) === null || _a === void 0 ? void 0 : _a.tblPeople);
matrix-confbot[190167]:                                                                                         >
matrix-confbot[190167]: TypeError: Cannot read property 'database' of undefined
matrix-confbot[190167]:     at Object.<anonymous> (/app/lib/backends/penta/db/PentaDb.js:25:213)
matrix-confbot[190167]:     at Module._compile (internal/modules/cjs/loader.js:1085:14)
matrix-confbot[190167]:     at Object.Module._extensions..js (internal/modules/cjs/loader.js:1114:10)
matrix-confbot[190167]:     at Module.load (internal/modules/cjs/loader.js:950:32)
matrix-confbot[190167]:     at Function.Module._load (internal/modules/cjs/loader.js:790:12)
matrix-confbot[190167]:     at Module.require (internal/modules/cjs/loader.js:974:19)
matrix-confbot[190167]:     at require (internal/modules/cjs/helpers.js:101:18)
matrix-confbot[190167]:     at Object.<anonymous> (/app/lib/backends/penta/PentaBackend.js:5:19)
matrix-confbot[190167]:     at Module._compile (internal/modules/cjs/loader.js:1085:14)
matrix-confbot[190167]:     at Object.Module._extensions..js (internal/modules/cjs/loader.js:1114:10)

Regards.
\_o<